Vacuum sanding devices have been known for sometime. They usually take the form of circular rotary grinders or double action sanders although patents have also issued for vacuum sanders of a rectangular format. Examples of such rectangular vacuum sanders are to be found in U.S. Pat. Nos. 4,062,152 of Dec. 13th, 1977 Mehrer, 3,123,946 of Mar. 10th, 1964 Hoveland, 2,499,933 of Mar. 7th, 1950 Smul. In circular vacuum sanding devices, examples may be found in Applicant's Canadian Patent 1,080,477 Aug. 1st, 1980, Canadian Patent 931,761 to Olmoen, U.S. Pat. Nos. 3,785,092 Hutchins, 2,895,266 Statler, U.S. Pat. Nos. 4,164,101 Robert and 3,862,521 Jan. 28th, 1975.
There are several disadvantages in the construction of the prior art patented devices. Many of them are complicated, incorporating too many moving parts and are therefore expensive to manufacture and maintain. Others do not provide adequate suction adjacent the immediate work area and, if they do, they sometimes have upper housings that are spaced substantially outwardly of the backup pads or sanding blocks so that the sanding blocks can never reach deeply into corners or hard-to-get-at areas.